Driven pulley rotating?

I have a new to me Polaris 250 trail Boss 2 wheel drive ATV. With clutch cover off, I can see the driven pulley rotate at idle. I have the idle speed down as far as it will go to keep the engine running. Which is not a very fast rpm.
Not having a machine like this before, doesn’t the driven pulley need not to be rotating to shift into forward or reverse? What is normal for the driven pulley at idle, not to be rotating? I don’t want to mess up the transmission.
thanks